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Table of Contents
- Course Home
- Objectives
- Matching Exercise
- Introduction
- Anatomy: The Heart
- Anatomy: The Vessels
- Physiology: Introduction
- Physiology: Review of Circulation
- Physiology: The Cardiac Cycle
- Physiology: Innervation of the Heart
- Cardiac Electrophysiology: Introduction
- Cardiac Electrophysiology: Electrolytes
- Cardiac Electrophysiology: Cardiac Automaticity
- Cardiac Electrophysiology: The Cardiac Conduction System
- Cardiac Electrophysiology: Myocardial Contraction
- Sample Cases
- Case 1: Cardiac Tamponade
- Figure 1: Assessment
- Figure 2: Management
- Case 2: Cocaine Overdose
- Figure 3: Assessment
- Figure 4: Management
- Case 3: Hemorrhagic Shock
- Figure 5: Assessment
- Figure 6: Management
- Conclusion
- References
- Bibliography
Cardiac Electrophysiology: Electrolytes
Introduction:
The spontaneous generation of cardiac electrical signals, as well as their propagation, is due to alterations in electrolyte concentrations. The major electrolytes that are involved in this process include: Sodium, Calcium, Potassium, Magnesium, and Chloride.
Sodium:
Sodium plays a vital role in automaticity, which is a property characterized by the heart’s ability to generate spontaneous, repetitive contraction stimuli.
Calcium:
Calcium is also essential for automaticity and, in addition, plays a vital role in cardiac contractions.
Potassium:
Potassium’s role in the heart is to reset the repetitive firing system so that it can quickly become active after each electrical stimulus it generates.
Magnesium and Chloride:
The roles of Magnesium and Chloride are unclear, but low levels of these electrolytes impair the replacement and functioning of Sodium, Calcium, and Potassium, thus altering overall heart activity.
The Importance of Proper Electrolyte Concentration Balance:
Balance of the concentrations of electrolytes is important, as either an increase or decrease in electrolyte levels can alter the function of the heart. For example, hypercalcemia (or too much calcium) can result in increased cardiac contractility, while hypocalcemia (or too little calcium) can depress the contractility of the heart and cause electrical irritability. As another example, hyperkalemia (or too much potassium) decreases the automaticity and conduction of the heart, while hypokalemia (or too little potassium) can increase electrical irritability of the heart.